System and apparatus for cleaning bar grid

ABSTRACT

An automatic rake is provided for a bar grid which bar grid is mounted in a flume adjacent a waste disintegrator. The rake is preferably provided with a plurality of fingers extending between the bars of the grid and is reciprocated by a motor and is provided with a second motor member which is adapted to lift the rake away from the bar grid if an obstruction is met. Automatic means are provided so that when the obstruction is sensed, the rake will reverse itself and go to the bottom of the grid again. The arrangement is such in combination with a waste disintegrator that the material from the grid will be raked into the path of the disintegrator to be pulverized therein.

United States Patent [1 Teague et al.

[. 1 Dec. 24, 1974 SYSTEM AND APPARATUS FOR CLEANING BAR GRID [73] Assignee: General Signal Corporation, New

York, NY.

221 Filed: July 11, 1973 21 Appl. No.: 378,139

Related U.S. Application Data [62] Division of Ser. No. 275,914, July 28, 1972.

3,362,650 l/l968 Tracy 241/46 R X Primary ExaminerR0y Lake Assistant Examiner-E. F. Desmond Attorney, Agent, or Firm-Barlow & Barlow [57] ABSTRACT An automatic rake is provided for a bar grid which bar grid is mounted in a flume adjacent a waste disintegrator. The rake is preferably provided with a plurality of fingers extending between the bars of the grid and is reciprocated by a motor and is provided with a second motor member which is adapted to lift the rake away from the bar grid if an obstruction is met. Automatic means are provided so that when the obstruction is sensed, the rake will reverse itself and go to the bottom of the grid again. The arrangement is such in combination with a waste disintegrator that the material from the grid will be raked into the path of the disintegrator to be pulverized therein.

4 Claims, 5 DrawingFigures PATENTEDBEE241974 $856,216

sum 1 o 3 FIG.2

PATENHED 3,856,216

sum 2 9 3 FIG.4

PATENHED 3,856,216

SHEET 3 OF 3 PRESSURE SEQUENCE vALvE 4 wAY DIRECTIONAL VALVEGZ as Y 6/ DRAIN PREssURE SEQUENCE Y vALvE DRAIN 6.9 Rildsg 56 /59 64 v I WAY DIRECTIONAL Y vALvE DRA 70 55 MF PRIORITY vALvE- DISINTEGRATOR HYDRAULIC MOTOR Y 7 C IIII E vALvE RELIEF VALVE 52 5/ HYDRAULIC PF PUMP ELECTRIC MOTOR sTRAINER FIGS RESERVOIR 2O GALS.

SYSTEM AND APPARATUS FOR CLEANING BAR GRID This is a division of application Ser. No. 275,914 filed July 28, 1972.

BACKGROUND OF THE INVENTION In primary treatment of waste water there takes place essentially a liquid/solid separation which is accomplished by screening. Screenings will remove coarse solids and are generally formed by placing a plurality of bars in parallel in the form of a rack, and these racks are either hand or mechanically raked. The screen grid needs to be of such dimensions and configurations that undesirable accumulations do not occur thereon since a head loss will take place in the flume channel feeding the bar grid. The bar grids are therefore usually cleaned by the use of rakes that are operated either by hand or mechanically. The mechanical rakes suffer primarily from the problem that if the rake is placed on the face of the screen the mechanism quite frequently forces the tines of the rake to penetrate the debris and if the tines strike a particularly heavy piece, they quite often can become damaged. It also has become common to remove the material from a bar grid into some form of a collector such as a gutter belt conveyor, hopper car, or the like, but as can be seen this involves more transport of the debris material which must eventually be comminuted. It thereforewas more practical to associate a bar grid with a single faced grinder or disintegrator which utilizes flow for the grinding process and to discharge the material into this flow path to the face of a disintegrator.

SUMMARY OF THE INVENTION The present invention permits the use of a mechanical rake oriented on the face of a bar grid, which bar grid is inclined to the flow that aids in the reciprocation of the rake up and down the face of the bar grid. The reciprocation of the rake is provided by a motor means that is attached thereto and a second motor which positions the rake in contact with the bar grid or lifted therefrom. At the lower end of the bar grid the rake will lie against the grid with its tines in between the spaces and will move itself upwardly on the incline delivering the debris over the end of the bar grid into the path of the disintegrator with is arranged in the flume to receive a portion of the direct flow. A second motor will then lift the rake and permit it to return to the bottom of its stroke out of contact with the bar grid. Should, for example, the rake on the upward stroke reach an obstruction, means associated with the motor will sense the overload and lift the rake from contact with the bar grid and return it to the bottom of the stroke to begin the cycle all over again. When this type of apparatus is used together with a waste disintegrator or comminutor, the material may be ground up in the waste disintegrator, being broken up into fragments small enough so that they may safely pass through the plant. In the preferred form of bar grid or'screen, the flume may be divided in such a way that direct flow is provided to impinge upon the waste disintegrator and side flow is directed towards the bar screens which may be mounted effectively inside diverting channels and there may be one or more with this orientation. In this manner of arrangement direct flow is insured against the waste disintegrator which is necessary for its proper operation since it is a single face grinder.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of a preferred form of system employing bar grids located in a flume with diversion channels;

FIG. 2 is a sectional view taken substantially on lines 22 of FIG. 1 with parts omitted for clarity and showing particularly the flow pattern of the solids;

FIG. 3 is an end elevational view partly broken away of FIG. 1 showing the cleaning system for the bar grid;

FIG. 4 is an end view in elevation looking at one of the bar grids; and

FIG. 5 is a hydraulic schematic diagram showing the manner in which the system operates.

DESCRIPTION OF THE PREFERRED EMBODIMENT The system as a whole is best illustrated in FIG. 1 where in plan the main flow channel is shown as divided into three channels, there being a direct impingement channel that leads directly to a disintegrator generally designated 12 and a pair of side channels 14 and 16, all of which discharge into channel 17. The channels are formed by concrete walls 18 and 19 which direct the flow as shown substantially by the arrows, channels 14 and 16 discharging through openings 20,

21. Bar grids generally designated 22 and 22' are located in channels 14 and 16 and comprise a plurality of spaced longitudinally extending bars 23, 23' which are secured to a plurality of transverse members 24, 24 that are in turn welded to frames 25, 25

The bar grid cleaning mechanism is shown in FIG. 4 as comprising a rake member 26 which has a plurality of fingers 27 that extend downwardly between the bars 23 centrally of the rake 26. At 28, there is affixed a motor means in the form of a piston rod 29 extending from a hydraulic double acting cylinder 30. The motor 30 is mounted as at 31 to a support framework 32 which framework can be made up of a number of metal channels that are mounted in the flume in suitable manner adjacent the waste disintegrator. The second motor is provided and this motor is pivotally mounted on the lower end of the motor 30 as at 41. It is illustrated as being a double acting hydraulic cylinder whose other end is pivotally mounted to a portion of the support frame 32 as at 42.

To understand how the system operates, reference should be had to FIG. 5 where the hydraulic circuit is illustrated in diagrammatic form. Basically it will be seen that there is a hydraulic reservoir with the main hydraulic pump 51 driven by an electric motor 52. The hydraulic pump takes its supply through a strainer 53 and delivers it to a diversion or priority valve 54, one output of which has a lead to a hydraulic motor 55. The other output leads to a four-way directional valve 57. Another output from the pressure pump 51 moves through check valve 58 to a differential pressure operated four-way valve 60. Valve 60 feeds hydraulic fluid to the hydraulic motor 40 which serves to position the rake either away from or against the bar grid and in addition this four-way valve 60 will operate differential pressure operated four-way valve 57. As shown in the diagram, pressure applied through valve 60 will cause the motor 40 to operate to a position where the rake engages the bar grid. When the piston in the motor 40 reaches the end of its stroke, pressure will rise in hydraulic line 59 and be applied to operator 61 moving the valve 57 to the position as shown in the diagram and apply pressure to the lower end of the rake motor 30 causing the rake to move upwardly as shown in the drawing. When the rake reaches the top of the stroke, or in the alternate if debris on the rake jams the scraper before it reaches the top of the stroke, pressure in the hydraulic line 63 will rise going to a maximum value and pressure sequence valve 64 will operate which will now allow hydraulic pressure to reach the operator 65 reversing four-way valve 60. When this occurs, hydraulic pressure is now fed out over line 66 which will now apply pressure to hydraulic motor 40 casing the rake to rise away from the bar grid. When the motor 40 has moved to its extreme position, pressure will rise and cause operator 62 to move valve 57 to a position to supply hydraulic pressure overline 67 to the top of rake cylinder 30 causing the rake now to move downwardly. At the same time the pressure that was applied to the sequence valve 64 will now drop since line 63 is connected to a drain and further the pressure on the operator 65 will drop leading through check valve 68. When the rake reaches the bottom of the stroke, the pressure in the hydraulic line 67 will rise going to a maximum value and this will operate pressure sequence valve 69 which will now apply pressure to operator 70 which will operate four-way valve 60 back to the direction as shown in the drawing applying pressure to the rake guide cylinder to cause the rake to engage the bar grid and the cycle will now repeat itself.

From the foregoing it will appear that there has been provided a means for cleaning bar grids by removing turn to the bottom of the grid to re-cycle in an upward stroke so that it will eventually pull the debris to the top of the grid and deposit it in front of the disintegrator. The rate of frequency at which the rake is reciprocated may be varied but will ordinarily be on the order of three times per minute. The bar grids are preferably debris therefrom and depositing it in the face ofa disinsloped as shown in FIGS. 2 and 3 and will ordinarily be at an angle of from 30 to 60 with respect to the horizontal.

We claim:

1. In a system including a flume in which waste material flows, a grid for separating and retaining large solid particles of waste matter from said waste material and a disintegrator for reducing the size of said solid particles, the improvement comprising a plurality of vertical walls providing at least two individual inlet channels and a common discharge channel, one inlet channel terminating in a wall containing a disintegrator, the other inlet channel directing the flow through the grid, said disintegrator and said grid discharging into said common discharge channel, said grid having an automatic rake mechanism for periodically removing said solid particles from said grid and directing said particles to said disintegrator.

2. In a system in accordance with claim 1 wherein said rake is moved from a first position to a second position by fluid motors.

3. In a system in accordance with claim 2 wherein said motors are periodically actuated by valve means including a pressure responsive valve that causes said motors to return said rake to said first position if said rake impinges on a solid particle it cannot move.

4. In a system in accordance with claim 1 wherein the grid extends at an angle to the direction of flow, the leading edge of the grid being at the bottom of one inlet channel of the flume and the upper edge of the grid being adjacent the inlet to the disintegrator. 

1. In a system including a flume in which waste material flows, a grid for separating and retaining large solid particles of waste matter from said waste material and a disintegrator for reducing the size of said solid particles, the improvement comprising a plurality of vertical walls providing at least two individual inlet channels and a common discharge channel, one inlet channel terminating in a wall containing a disintegrator, the other inlet channel directing the flow through the grid, said disintegrator and said grid discharging into said common discharge channel, said grid having an automatic rake mechanism for periodically removing said solid particles from said grid and directing said particles to said disintegrator.
 2. In a system in accordance with claim 1 wherein said rake is moved from a first position to a second position by fluid motors.
 3. In a system in accordance with claim 2 wherein said motors are periodically actuated by valve means including a pressure responsive valve that causes said motors to return said rake to said first position if said rake impinges on a solid particle it cannot move.
 4. In a system in accordance with claim 1 wherein the grid extends at an angle to the direction of flow, the leading edge of the grid being at the bottom of one inlet channel of the flume and the upper edge of the grid being adjacent the inlet to the disintegrator. 